1. Field of the Invention
The invention relates to a control for memory storage access for coupled mask-programmed microcontrollers, in particular employed in applications for memory storage programmable control in the low-cost region, with at least two microcontrollers accessing through a joint data bus/address bus onto a joint program memory storage/data memory storage, wherein one of the microcontrollers operates as master and one or more of the microcontrollers operate as slaves, and wherein the communication of the microcontrollers among themselves is controlled based on hardware construction and software operations.
2. Brief Description of the Background of the Invention Including Prior Art
In order to achieve an increase in power of electronic apparatus, in particular in applications for memory storage programmable control in the low-cost region, the concept of distributed systems spreads and is more and more successful. Such a distributed system is based on the coupling of several microcontrollers each representing a central unit, wherein the different tasks of the coupled microcontrollers are processed autarch, autonomous, independently, and parallel. The microcontrollers communicate in this case with each other for the purpose of synchronization and data exchange. If the microcontrollers are not constructed for a multi-processor coupling, wherein one of the microprocessors can stop the second microprocessor, then the coupling is realized according to the state of the art through a dual-port RAM or through a connection of the port pins or through a serial communication. According to the state of the art, a microcomputer has become known in the German Patent Document DE 30 07 519 C2, wherein the microcomputer operates as a master with a like microcomputer operating as a slave, wherein the microcomputers communicate with each other by means of a serial coupling through port pins and serial interfaces. The company brochure Microcontroller, Databook, National Semiconductor Corp., Santa Clara, Calif., 1988, pages 4-35 to 4-53 describes a microcontroller, which is also provided for a serial communication in a master-slave method with a like microcontroller. The reference describes a master-slave method which is capable of operating on a bus, wherein the master in each case multiplexes one of several slaves.
It is noted that the conventional methods are either associated with high cost or require increased equipment expenditures or need a substantial processing time.
In a mask-programmed memory storage, the contents of the memory of each element is determined at the production time with a mask, compare for example German Industrial standard DIN 444 76, part 1, January 1982.
Monolithical microprocessors, generally formed as a single-chip, include, in addition to their computing function, a data memory storage and a program memory storage. The memory storages are fixed-programmed and in fact generally by means of a mask. The mask programming is a process, where a specific bit pattern is achieved for the predetermined non-accessing of binary positions.
A master-slave arrangement is an arrangement of two bistable circuits, which effects that the second one of the two bistable circuits, which is called slave, reproduces the starting configuration of the first one of the bistable circuits, and therefore the first bistable circuit is called master. The transition of information from the master part to the slave part is induced by a suitable signal, compare for example German Industrial Standard DIN 418 59, sheet 10.
A master-slave arrangement is an arrangement of a control connection including two or more computers, where one computer operates as master and the other units operate as slaves. The master controls for example the data transmission protocol and coordinates the control and execution functions of the slave(s).
Handshaking relates to a required sequence of signals for communication between system functions. The IO bus-protocol for a system defines its handshaking requirements. Each signal requires a response or reply to complete an input-output operation in an asynchronous IO input-output system.
In particular, handshaking is a central processing unit terminal interface process that prevents overrun and acknowledges signalling. The central processing unit operating as a transmitter sends a signal in response to a request from the central processing unit operating as a receiver, which central processing unit operating as a receiver then sends an acknowledgment signal to the central processing unit operating as a transmitter. Thus, in general, handshaking is an exchange of predetermined signals establishing contact between two data sets.
Devices having differing reaction speeds communicate with each other and come to an agreement relating to the start and the end of an exchange of data.
In the case of the present invention, the agreement between the devices does not relate to the exchange of data between the devices but to an agreement relating to an access control relative to the external program memory storage.